The application of present invention relates to and incorporates herein by these references co-pending patent applications entitled xe2x80x9cMethod and Apparatus for Controlling Trains by Determining a Direction Taken By a Train Through a Railroad Switchxe2x80x9d by David H. Halvorson, Joe B. Hungate, and Stephen R. Montgomery, and entitled xe2x80x9cMethod and Apparatus For Using Machine Vision to Detect Relative Locomotive Position On Parallel Tracksxe2x80x9d by Jeffrey D. Kernwein, both of which were filed on even date herewith, and are subject to assignment to the same entity as the present application.
The present invention generally relates to railroads, and more specifically relates to train control systems and even more particularly relates to automatic and remote sensing of the passage of rail switches.
In the past, train control systems have been used to facilitate the operation of trains. These train control systems have endeavored to increase the density of trains on a track system while simultaneously maintaining positive train separation. The problem of maintaining positive train separation becomes more difficult when parallel tracks are present. Often, parallel tracks exist with numerous cross-over switches for switching from one track to another. It is often very difficult for electronic and automatic systems such as train control systems to positively determine upon which of several parallel train tracks a train may be located at any particular time. For example, when tracks are parallel, they are typically placed very close to each other with a center-to-center distance of approximately fourteen (14) feet.
In the past, several different methods have been attempted to resolve the potential ambiguity of which track, of a group of parallel tracks, a train may be using. These methods have included use of global positioning system receivers, track circuits and inertial navigation sensors. These prior art approaches of determining which track is being used each have their own significant drawbacks. Standard GPS receivers are normally incapable of positively resolving the position of the train to the degree of accuracy required. The separation of approximately fourteen (14) feet between tracks is often too close for normal GPS receivers to provide a positive determination of track usage. The use of differential GPS increases the accuracy, i.e. reduces the uncertainty in the position determined. However, differential GPS would require that numerous remotely located differential GPS xe2x80x9cstationsxe2x80x9d which include transmitters be positioned throughout the country. The United States is not currently equipped with a sufficient number of differential GPS transmitting stations to provide for the accuracy needed at all points along the U.S. rail systems.
The track circuits which have been used in the past to detect the presence of a train on a particular track also require significant infrastructure investment to provide comprehensive coverage. Currently, there are vast areas of xe2x80x9cdark territoryxe2x80x9d in which the track circuits are not available. Additionally, these track circuits are subject to damage at remote locations and are susceptible to intentional sabotage.
The inertial navigation sensors proposed in the past have included both gyroscopes and acceleration sensors. The gyroscopes are capable of sensing a very gradual turn; however, gyros with sufficient accuracy to sense such turns are very expensive. Acceleration sensors, while they are less expensive than sensitive gyros, typically lack the ability to sense the necessary movement of a train especially when a switch is being made from one parallel track to another at very low speeds.
Consequently, there exists a need for improvement in train control systems which overcome the above-stated problems.
It is an object of the present invention to provide a train control system having enhanced positive train separation capabilities.
It is a feature of the present invention to include a train control system having capabilities for sensing the direction a train takes through switches.
It is an advantage of the present invention to reduce the ambiguity of track occupancy which is often present when trains operate within a group of parallel tracks.
It is another object of the present invention to improve position determination accuracy of trains.
It is another feature of the present invention to include a sensor on board the train for sensing the rotation of a locomotive truck as it pivots from its normal position.
It is an advantage of the present invention to provide additional information regarding the train position which can be used to supplement and update other positional information, including GPS signals.
It is yet another object of the present invention to detect curves in the tracks.
It is yet another feature of the present invention to monitor the duration of the rotation of the locomotive truck, as well as the extent of the rotation of the locomotive truck over a period of time after a significant truck rotation has occurred.
It is another advantage of the present invention to provide an additional source of information relating to passage of a locomotive through a curve in the track.
The present invention is a method and apparatus for controlling trains by detecting the extent, duration and direction of locomotive truck rotation as the locomotive passes through railroad switches and/or turns, which is designed to satisfy the aforementioned needs, provide the previously stated objects, include the above-listed features, and achieve the already articulated advantages. The invention is carried out in an xe2x80x9cambiguity-lessxe2x80x9d system in the sense that the track ambiguity is greatly reduced by providing information on the passage of switches, and the direction a train has taken through a switch, as well as the passage of turns in the track.
Accordingly, the present invention is a method and apparatus for determining the passage of a locomotive through a switch or a turn by monitoring truck rotation.